Circuit Description
The PCM has a memory area where it stores certain data it needs to save when the key is turned OFF. This area is called Keep Alive Memory. This diagnostic test monitors the PCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC P0603 will set.
Conditions for Setting the DTC
Test Condition
Test continuously.
Failure Condition
Keep alive memory checksum does not match previous checksum.
Action Taken When the DTC Sets
| • | Clear all keep alive memory locations. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | No message will be displayed. |
Conditions for Clearing the DTC
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Diagnostic Aids
If the battery has been disconnected for any reason DTC P0603 will set. The PCM keeps a running check on the memory; if memory changes it resets. An intermittent loss of power or ground to the PCM will cause a reset.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
2 | Using a scan tool check for DTCs. Are any other DTCs set? | -- | Diagnose other DTCs | Refer to Diagnostic Aids |
